1. Field of the Invention
This invention relates to a recording medium for magnetically recording information signals and a recording/reproducing method and apparatus for exchange processing of malfunctioning areas of the recording medium for recording the information signals.
2. Description of the Related Art
In a magnetic recording device, defective sectors are detected at the time of disc shipment or disc formatting and physical block addresses of the defective sectors are removed from the allocation to the physical block addresses by way of performing sector slipping. Also, if there occurred a defective track, the track in its entirety is removed from the allocation to the logical sectors, by way of performing track slipping.
As for the defective sectors removed by the sector slipping and for the defective tracks removed by the track slipping, there are such a system in which the sectors or tracks are simply put out of use to render the capacity available for the user variable, and such a system in which substitution sectors or tracks for the sectors or tracks removed by the slipping are provided outside of the usual user area.
In the former case, the sectors or tracks other than those found to be defective can be used in their entirety for writing user data, thus assuring a high recording medium using efficiency. However, this using manner poses a problem in an exchange recording medium such as a floppy disc, although there is no problem raised in case of a non-exchange medium, such as a hard disc. That is, there are occasions wherein the effective disc capacity is varied from disc to disc, such that there is a possibility that copying of the entire disc contents cannot be made from one disc to another.
In the latter case, since a constant format capacity can be assured at all times, the above-mentioned inconvenience in disc copying is not raised. However, since the substitution sectors or tracks need to be provided outside the user area, part or all of the spare region is not unusable.
Thus, the conventional defect processing method used in the conventional magnetic recording device is founded on the basic principle of not using his spare region.
As for the method of associating the physical block addresses with the logical block addresses, there are such a method of disc surface based association, a method of disc surface based association provided that one of the disc surfaces is processed for association and subsequently the other disc surface is processed for association from the opposite direction, and a method of zone based association using separate zones provided from the outset on the disc surfaces.
As for the method of providing spare sectors in case such are provided as the substitution sectors for sector slipping, there are a variety of methods, such as a method of providing the spare sectors in each track, a method of providing the spare sectors in each zone or a method of providing the spare sectors at a pre-set position on the disc.
The associating method for the logical block addresses and the physical block addresses, including defect management, is associated with a non-exchange type recording medium. That is, in selecting the associating method for the physical block addresses and the logical block addresses or the spare sector position setting method, meritorious characteristics, such as short seek time or high transfer speed, or the non-sophisticated control algorithm, represent the criteria for selection.
Meanwhile, with the defect management system, termed slipping, employed in the conventional magnetic recording de-vice, it is not possible to cope with defects that occurred after start of the use of the disc, although it is possible to evade the initial disc defects from the outset.
Thus, for improving disc reliability, there is used a method of previously attaching redundancy bits for error correction prior to proceeding to data recording. If failure readout occurs, those parameters affecting playback characteristics, such as tracking or equalization, are changed on re-trying.
With the above-described conventional system, success in the next readout is not ensured even if readout has been made successfully on re-trying. Moreover, the fact that readout has been achieved only on re-trial with changed parameters means that the sector in question is hard to read such that the sector in question has been lowered in readout reliability.
Thus, with the conventional system, it has been difficult to assure data reliability in future with respect to defects produced during use or otherwise proceeding with lapse of time.